Spinal fusion is a surgical procedure used to join two or more vertebrae. The procedure is primarily used to eliminate pain, which can be caused by a number of conditions, such as degenerative disc disease, vertebral fracture, spondylolisthesis and other diseases that cause instability of the spine.
In most spinal fusion procedures, spinal fixation rods are attached to vertebral implants, which are first secured to adjacent vertebrae. The vertebral implants generally include a bone anchor seat, a collet disposed inside the anchor seat, and a bone anchor with a head portion attached to the collet. The spinal fixation rod is inserted through the collet and fixed in place by a locking cap that attaches to the collet.
The placement of a spinal fixation rod within a vertebral implant typically required a large opening in a patient's body to provide a surgeon with the visibility required at the surgical site. Recently, minimally invasive surgeries have become more common and desirable as they reduce complications during surgery and recovery time after surgery. Minimally invasive spinal fusion surgery presents a number of unique challenges including: retention of the spinal fixation rod within the surgical instrument during the insertion process; manipulation of the spinal fixation rod while it is inside the patient; and proper alignment and positioning of the spinal fixation rod relative to the vertebral implants.